1. Field
The following description relates to a left-right independent steering control system and a method thereof, particularly a left-right independent steering control system that controls the other steering system such that the steering angles of both wheels satisfy Ackerman condition, when the steering angle of a vehicle is not controlled in accordance with steering input from a driver due to a breakdown in any one of left wheel and right wheel steering systems of the vehicle, and a method thereof.
2. Description of the Prior Art
Concerning the steering control system in vehicles, various steer-by-wire (hereafter, SBW) vehicle steering systems that can freely determine steering reaction torque (or steering reaction force) applied to a steering wheel and the steering angle of a vehicle that is steered have been proposed. Those SBW vehicle steering systems for vehicles generally use a mechanical backup system at the middle of a column shaft for mechanically coupling steering input unit and output unit, using a mechanism backup system, in a back-up mode (or a fail-safe mode) that is operated by a breakdown in an SBW system.
Using a cable backup system (flexible torque transmission unit) as the mechanical backup system is very effective in terms of improving the degree of freedom in design of the layout of a cockpit, reducing vibration and noise transmitted to the steering wheel through steered wheels from a road, and removing shocks in front collision.
In particular, Korean Patent Registration No. 10-0745915 providing such a mechanical backup system discloses a configuration that makes sure of effective reduction of the minimum rotational radius by a variable pitch dual rack assembly even in a backup mode by mechanically connecting a steering input unit (steering wheel) and a steering output unit (variable pitch dual rack assembly), using a clutch, when an SBW system breaks.
However, the mechanical backup system has a problem in that the manufacturing cost is high because a specific mechanical configuration is required in addition to the SBW system, such that the entire weight of a vehicle increases. The increase in the entire weight of a vehicle causes an increase and inefficiency in use of fuel. In particular, the mechanical backup system is in the backup mode, when a vehicle is in a normal state, but it operates after a breakdown occurs, and thus, it is practically difficult to be mounted on a vehicle that normally operates, which is very inefficient.